Presumabaly we're not allowed to mention the too-tight standing martinggale being used for jumps?..........
Other than that thought you've got a fairly good position. You stirrups are a little short however, even for jumping - you look like you're perched on top of the horse, making your centre of gravity too high.
If you felt they were too long once you'd put them down a bit, it suggests you ride too short on the flat. Lots of no stirrup work and gradually lenghtening your stirrups will sort that.
You also look tense - you've got that 'scrunched up' look about you. Try to open your shoulders a little, bringing them back. Doing that will make you sit up too, and allow you to lower your centre of balance a little as you relax your back and seat. It will also allow you to lengthen you legs and therefore cope with your stirrups being a couple of holes longer.
Can't tell much from the jumping photo but you look like you've got a secure position with your heels down. But no leaning on the neck!